Estimation and validation of total digestible nutrient values of forage and concentrate feedstuffs

Abstract

Total digestible nutrient (TDN) values represent utilisable energy contents of feedstuffs, and these are extremely important values in order to provide adequate energy supply for livestock. This study aimed to estimate and validate TDN values of forage and concentrate feedstuffs from their nutrient contents. Nutrient composition data were obtained from BR CORTE database, comprised of 86 forage and 36 concentrate feedstuffs. The data included contents of dry matter (DM), organic matter (OM), ash, neutral detergent fiber (NDF), lignin, non-fiber carbohydrate (NFC), ether extract (EE), crude protein (CP) and TDN. A correlation analysis was conducted among the nutrient composition parameters for forage and concentrate. Data were then randomly divided into two parts, the first part (two-third of data) was used to estimate TDN whereas the second part (one-third) was used to validate the estimated TDN. Estimation of TDN was performed by employing a multiple linear regression method and it was validated by plotting between observed and estimated TDN. Results revealed that TDN in forage was negatively correlated with NDF (P<0.001) and lignin (P<0.05), but positively correlated with NFC and EE contents (both at P<0.001). Such pattern was similarly obtained with that in concentrate. Prediction equations of TDN in forage and concentrate were TDN = 0.479 NDF + 0.704 NFC + 1.594 EE + 0.714 CP and TDN = 0.323 NDF + 0.883 NFC + 1.829 EE + 0.885 CP, respectively. Values of estimated and observed TDN both in forage and concentrate were closely similar. It is concluded that TDN can be accurately estimated from nutrient composition data.